Method of forging gear blanks



Patented Oct. 20, 1936 NTI-:D STATES PATENT OFFICE 8 Claims.

The invention relates to the forging of gear blanks and the like and more particularly'to a method of precision forging such parts so accurately that no machine work is required upon the gear blanks excepting the cutting of the gear teeth.

Under present practice forged gear blanks and the like are produced in dies having considerable draft which is necessary in order that the forgings will not stick or bind in the dies in which they are formed. This draft in the dies produces a considerable peripheral taper from the center toward both sides of the forged gear blank as well as a considerable oppositely disposed flare in the center opening of the forged gear blank. This necessitates machining of the peripheral portion as well as of the central opening in the gear blank before the blank is in condition for cutting of the gear teeth thereon.

The present improvement contemplates the production of precision forgings for gear blanks and the like which eliminates this peripheral taper as well as the aring of the center opening of the forged blank, thus eliminating machining of either the outside or inside of the forged gear blank.

The objects of the improvement may be accomplished by first forging the gear blank or the like with the usual draft or taper at the periphery and within the center opening thereof, the top and bottom sides of the forging being flared or inclined toward the periphery and the central opening, producing an excess of metal at these points. The ash and web are then sheared in the usual manner and the hot forging thus produced is placed in a press equipped with dies shapedto produce the desired finished form of gear blank, and therein pressed to the desired shape, the excess metal at these high points of the forging being displaced vso as to produce a. precision forged gear blank having straight sides around its periphery and center opening.

An embodiment of the invention is illustrated in the accompanying drawings, in which Figure 1 is an elevation of a bar blank from which a forged gear blank or the like may be produced;

Fig. 2, an elevation of the blank after it has been hammered to the proper shape for placing in the forging dies;

Fig. 3, a transverse sectional view through the partly completed forging as it emerges from the forging dies;

Fig. 4, a similar view after the flash and web have been sheared from the forging; and

Fig. 5, a transverse sectional view through the improved precision forging produced by the method to which the invention pertains;

Fig. 6, a sectional elevation of a portion of the press and dies in which the final operation is performed showing the partly completed product as illustrated in Fig. 4 in position in the lower die of the press; and

Fig. 7, an enlarged sectional view of the dies shown in Fig. 6 shown in the closed or operative position showing a completed precision forging therein. f

Similar numerals ref er to similar parts throughout the drawings.

In carrying out the invention a cylindric bar blank as indicated at I0 in Fig, 1 is heated to a forging temperature and is then given one or two blows by a drop hammer to flatten the same to substantially the shape shown at IIla in Fig. 2.

The still hot blank IIJa is then placed in the dies of a drop hammer which are shaped to pro`- duce the partly finished forging shown in Fig. 3. These dies have the usual draft producing the oppositely disposed tapers I I around the periphery of the forging while the center opening I2 thereof is oppositely ared as shown at I3.

The dies used for this purpose are so shaped as to form an annular concavity I4 in the upper face of the forging, producing the high points I5 and I6 adjacent to the periphery and the center opening respectively. In like manner the lower die forms high points I'I and I8 on the lower side of the forging adjacent to the periphery and central opening respectively.

The usual flash I9 and web 20 are formed in the forging operation and while the forging is still hot, this flash and web are sheared in the usual manner, the partly completed product as shown in Fig. 4 being then placed in the lower die 2I of a press as shown in Fig. 6.

The bed 22 of this press is provided with the 'xed stem or plunger 23 of cylindric form which is located through an opening 24 in the lower die block 25, whereby the die block may be slidably moved in vertical direction upon the plunger. 'I'he lower die block 25 is suspended from the head 26 of the press as by the bolts 21 upon which the die block may slidably move vertically as will be later described.

The upper die impression 28 is formed in the movable head 26 of the press, having straight side walls to form the periphery of the gear blank'straight and is provided with the central opening 29 to receive the plunger 23 when the head is moved downward to close the dies upon the partly completed product, as shown in Fig. 7, pressing the hot forging into the shape shown at 30 in Figs. 5 and 7, the excess metal at the high points I5 and I'I being forced outward against the side walls of the upper die 2B, producing the straight peripheral wall 3|, while the excess metal at the high points I6 and I8 is forced inward against the plunger, producing the straight walls 32 ofthe central opening.

In like manner, as this excess metal is displaced, the fiat upper surface 33 and fiat lower surfaces 34 and 35 are formed upon the gear blank. The forging thus produced is accurate as to shape and size and needs no machining excepting the necessary cutting of the gear teeth in the peripheral portion thereof.

As the head 26 of the press is again raised, the dies will be separated leaving the finished forging upon the lower die and tightly surrounding the plunger 23 due to contraction of the cooling metal in the forging. As the head reaches the upper limit of its movement, as shown in Fig. 6, the die block 25 will be raised to the top of the plunger 23, sliding the forging upward off of said plunger so that it may be easily removed from the lower die.

kIt has been found in practice that the improved method of forging gear blanks and the like compensates for any inaccuracy or unevenness in the partly finished product as shown in Figs. 3 and 4, which may be due to wear in the dies for forming the same, since the plunger 23 cooperating with the dies in the press, as shown in Figs. 6 and 7, accurately centers the forging within the dies.

I claim:

l. The method of producing forged metal gear blanks and the like which comprises forging a. metal article having tapered side walls with an adjoining concaved face producing an excess of metal at the intersection of said side walls and said adjoining face and then subjecting said article while heated to pressure causing -said excess metal to flow into the side walls.

2. The method of producing forged metal gear blanks and the like which comprises forging a metal article having tapered side Walls with an adjoining face flared toward said side walls producing an excess of metal at the intersection of said side walls with said adjoining face and then subjecting said article while heated to pressure causing the metal in said flared portion to ow into the side walls.

3. The method of producing forged metal gear blanks and the like which comprises forging a metal article having tapered side walls and a flared opening with an adjoining concaved face producing an excess of metal at the intersections of the concaved face with the side walls and with said ared opening and then subjecting said article while heated to pressure fiattening said concaved face and causing the excessmetal therefrom to flow into the side walls and the walls of said opening.

4. The method of producing a forged gear blank and the like which comprises forging an article with oppositely taperedA side walls and an oppositely flared central opening, the top and bottom faces thereof having an excess of metal adjacent to the periphery and adjacent to the central opening, and then subjecting said article while heated to pressure causing said excess metal to iiow into the side walls and the walls of the central opening.

5. The method of producing forged metal gear blanks and the like which comprises forging an article with oppositely tapered peripheral walls, the top and bottom faces thereof being concaved producing an excess of metal adjacent to the periphery of said articles, and then subjecting said article while heated to pressure causing said excess metal to flow into the side walls.

6. The method of producing forged metal gear blanks and the like which comprises forging a metal article having a flared opening, the face adjacent to the larger end of the opening being concaved producing an excess of metal surrounding the opening, and then subjecting said article while heatedto pressure causing said excess metal to iiow into the walls of the opening.

'7. 'Ihe method of producing' forged metal gear blanks and'the like which comprises forging a metal article having oppositely tapered side walls and adjoining faces flared toward the side walls producing an excess of metal at the intersection of said side walls and said adjoining faces and then subjecting the article while heated to pressure causing said excess metal to flow into the side walls to produce straight side walls and at adjoining faces.

8. The method of producing forged metal gear blanks and the like which comprises forging a metal article having oppositely tapered side Walls and an oppositely ared central opening and adjoining faces flared toward said side walls and toward said central opening producing an excess of metal at the intersections of saidfadjoining faces with the side Walls and with'tlie central opening, and then subjecting the ar ticle while heated to pressure causing said excess of metal to flow into the side walls and central opening to produce straight side walls and a straight central opening and fiat adjoining faces.

CHARLES A. BRAUCHLER. 

